Keeping maps updated - OpenStreetMap?

Both the Tolt-MacDonald and the Tokul maps are 4-5 years old and out of date. The switchbacks.com NWTrail set is still being updated but doesn't seem to have data newer than 2010 for those places. Many other places don't have good dedicated maps.

It's hard to update these maps... you have to know who made them in the first place, and then get the files from that person and use the same software. In practice, map "ownership" rarely gets handed off to new people with fresh energy, it seems.

And these days people ride with their GPS (Garmin, phone, ...) and want maps that can be loaded onto their gadget.

So... it seems the right place to create maps of trails these days is somewhere online where others can later edit what you did, somewhere wiki-like, such as... OpenStreetMap (www.openstreetmap.org)?

Thing is... I have no idea about the rules/policy/ethics of putting maps of private land trails on OSM. Is it "done"? Would the data be at risk of removal if the land owner requested it from OSM? Anyone know much about this?

Other suggestions about how we should keep maps? I'm looking for more than "just go to some GPS track site and download a track and follow it".

I'd be more interested in OpenStreetMap as it's inherently a community-driven tool, and there are tools that let you download (routable) maps from OSM to your Garmin... but use of use is important too, so it'd be intersting to hear experiences with either one.